(1) Field of the Invention
The present invention relates to an apparatus for periodically dispensing a fluid over an area by spraying. The present invention particularly relates to an electronic micro-dispensing apparatus for spraying pheromones in controlled amounts for a short duration in timed intervals to control insects in an outdoor setting such as an orchard.
(2) Description of the Related Art
Disruption of intraspecific chemical communication in insects can be accomplished by controlled release of synthetic pheromone to permeate the air within a crop (Carde and Minks, Control of moth pests by mating disruption: successes and constraints, "Annu. Rev. Entomol." 40:559-585 (1995). Commercial application of this principle for control of crop pests has led to the development of various devices that provide a pheromone reservoir and controlled release of the contents into the crop. A common method of pheromone release relies upon evaporation from small pieces of polymer impregnated or filled with pheromone. These devices can be relatively simple to construct and apply, but a high density of devices is required per unit area (McDonough et al, Performance characteristics of a commercial controlled-release dispenser of sex pheromone for control of codling moth (Cydia pomonella) by mating disruption, "J. Chem. Ecol." 18:2177-2189 (1992). Because the pheromones of some insect species are prone to oxidative and photodegradation (Millar, J. G., Degradation and stabilization of E8-E10-dodecadienol, the major component of the sex pheromone of the codling moth (Lepidoptera: Tortricidae) "J. Econ. Entomol." 88:1425-1432 (1995), precautions must be taken to shield labile pheromones to maintain behavioral activity throughout a full growing season. Pheromone also can be encapsulated in semipermeable polymeric membranes to produce a formulation that is applied directly onto the crop using standard agricultural technology (Vickers, R. A. and Rothschild, G. H. L., Use of sex pheromones for control of codling moth, pp. 339-354. In L. P. S. van der Geest and H. H. Evenhuis [eds.], Tortricid moths: their biology, natural enemies and control, Elsevier, Amsterdam (1991). These systems are usually characterized by first-order decay release rates, making long-term disruption with a single application problematic. Application from a high density of sources is conducted to uniformly permeate a crop with pheromone.
A more recently developed approach is to release the same total amount of pheromone per unit area, but from far fewer point sources, thus relying on wind movement to disperse the pheromone throughout the crop. The super-low density approach to dispensing pheromones has been tested with devices that provide intermittent release, to provide predetermined release rates and a stable environment for a large reservoir of pheromone prior to its release. Reduction of insect pest populations and crop damage has been reported in studies of the efficacy of this approach in field crops (Shorey et al, Widely separated pheromone release sites for disruption of sex pheromone communication in two species of Lepidoptera, "Environ. Entomol." 25:446-451 (1996); (Shorey et al, Disruption of pheromone communication in Spodoptera exigua (Lepidoptera: Noctuidae) in tomatoes, alfalfa, and cotton, "Environ. Entomol." 23:1529-1533 (1994); (Baker et al, Disruption of sex pheromone communication in the blackheaded fireworm in Wisconsin cranberry marshes by using MSTRS.TM. devices, "J. Agric. Entomol." 14:449-457 (1997), tree crops (Shorey, H. H. and Gerber, R. G., Use of puffers for disruption of sex pheromone communication among navel orangeworm moths (Lepidoptera: Pyralidae) in almonds, pistachios, and walnuts, "Environ. Entomol." 25:1154-1157 (1996); (Shorey et al, "Use of puffers for disruption of sex pheromone communication of codling moths (Lepidoptera: Tortricidae) in walnut orchards, "Environ. Entomol." 25:1398-1400 (1996), stored products (Mafra-Neto, A. and Baker, T. C., Timed, metered sprays of pheromone disrupt mating of Cauda cautella (Lepidoptera: Pyralidae) "J. Agric. Entomol." 13:149-168 (1996) and cranberry marshes (Baker et al, Ibid.); Fadamiro et al, Suppression of mating by blackheaded fireworm (Lepidoptera: Tortricidae) in Wisconsin cranberry marshes using MSTRS.TM. devices "J. Agric. Entomol." 15:377-386 (1998). The release devices have been referred to as "puffers" (Shorey et al, Ibid.) and "misters" (MSTRS.TM.) (Baker et al, Ibid), and though these studies have demonstrated the effectiveness of this approach, the devices are modifications of preexisting technology designed for indoor use. Hardware reliability is critical with this approach because at the low density of deployment, any failure to release pheromone has a large impact on the total release rate per unit area. This requirement may exceed the design limits of current technologies for super-low density release of pheromone, and for commercial use the grower would expect season-long operation.
In the past, pheromones for disruption of insect chemical communication have been released from impregnated solids like rubber and plastic in sizes ranging from sprayed microcapsules to foot-long strips hung on trees, open-ended hollow fibers where evaporation rate is controlled by size of the openings, and hollow polyethylene tubes having their lumen filled with chemical and heat-sealed at the end. Release rate from these "ropes" or other such releasers having an undiluted chemical reservoir is most preferably constant until the reservoir is exhausted.
A disadvantage of the above-mentioned dispersers is that they are perpetually "on" once deployed and cannot retain their chemical during periods when, due to pest life cycle, there may be no need to dispense the chemical. Dispensing the chemical only when needed is something that is economically desirable. Within the past two years, applied entomologists have adapted automatic aerosol dispensers to surmount this problem of wasting precious volatile chemicals by dispensing them indiscriminately over time. Automatic aerosol dispensers are used to dispense room deodorants or sometimes fumigants for insect pest control at timed intervals. At the intervals (e.g., 30 min. interval) a battery-powered motor turns gears attached to a lever that depresses the valve of an aerosol can, emitting a short pulse of can contents. Because many moth pests mate only at night, some automatic aerosol dispensers used for insect sex attractant release employ a photocell that precludes release in daylight. For this application, pheromone must be formulated with a propellant and packaged in a conventional spray can, which protects chemicals from exposure to the degradative factors of light and oxygen. The aerosol sprays onto a cloth pad from which it evaporates at a decreasing rate between pulses of spray.
Currently available are automatic aerosol dispensers which require a substantial amount of force (about 4 kg) to depress the aerosol can control valve. In addition, the mechanics and circuitry used to depress the aerosol control can valve on existing models are not maximally efficient and hence are more expensive than necessary. Furthermore, expensive and specialized equipment is required to charge or recharge an aerosol can. The currently available aerosol dispensers also have limited flexibility in control of their release of chemicals.
The related art has shown various types of automatic dispensing systems and apparatus. Illustrative are U.S. Pat. No. 3,305,134 to Carmichael et al; U.S. Pat. No. 3,523,646 to Waldrum; U.S. Pat. No. 4,272,019 to Halaby, Jr.; U.S. Pat. No. 4,473,186 to Alperin and U.S. Pat. No. 4,671,435 to Stout et al.
Carmichael et al describes an automatic spray device which will automatically and periodically dispense a compressed fluid. The device is used in connection with a pressure pack or aerosol container. The device comprises regulator valve mechanics connected to the pressure pack for regulating the exit flow of the propellant contained in the pressure pack and a diaphragm type valve in a chamber. The diaphragm type valve controls the flow of the fluid. When the propellant from the pressure pack accumulates and provides a proper pressure on the diaphragm valve, the valve will open, thus spraying the fluid. The device can be constructed with a separate container for the propellant or the fluid and propellant can be combined in the same container.
Waldrum describes a liquid sprayer which discharges the liquid in a direction opposite the direction of movement of the nozzle. The movement and direction of flow causes the uniform formation of droplets, which reduces the problem of drift.
Halaby, Jr. describes a programmable fluid sprayer apparatus for intermittent automatic delivery of an atomized fluid into the atmosphere for a selected duration of time at a selected frequency of delivery from at least one (1) adjustable fluid atomizing spray head. This apparatus is a complex system which permits only approved fluid to be dispensed for use in a particular area. Further, the spray nozzle means are spaced apart from the container of fluid to be atomized.
Aplerin describes a method and apparatus for spraying aerosols comprising small liquid or solid particles as fine mist over large distances while using minimal amounts of energy. The method and apparatus utilize the property of the ejector normally employed for momentum or thrust augmentation for dispersement of the liquid and solid aerosols over large distances with large divergence angles. The apparatus and method cause the substance to be sprayed to mix with a high velocity jet, thus causing an acceleration of the substance in the desired direction utilizing the drag force for projection over large distances rather than for deceleration and small spray distances.
Stout et al describes a solenoid operated valve. However, the nozzle and the valve are not joined together as in a fuel injector. The result is that there is less precision in the metering of the fluid to be sprayed.
The related art has also shown the use of solenoids to control the flow of liquids. U.S. Pat. No. 5,048,755 Dodds describes an irrigation system having a plurality of control valves for controlling the flow of water. The control valves can be individually controlled and can be solenoids. In addition, U.S. Pat. No. 5,074,443 to Fujii et al shows controlled dispensing of liquid through a syringe outlet by supplying constant air pressure to the interior of the syringe through an inlet and selectively retracting a valve shaft from a valve seat located at the syringe outlet to enable the pressurized liquid to be ejected through the outlet and out of the syringe. The valve shaft is retracted by a solenoid located in a housing assembly at the inlet of the syringe. U.S. Pat. No. 2,289,310 to Steel describes a paint gun having a double acting plunger activated by a solenoid coil. When the coil is activated, the plunger is retracted which opens the outlet port while at the same time closing the inlet port. The dual action of the plunger acts to limit the amount of paint sprayed during the activation time. U.S. Pat. No. 5,483,944 to Leighton et al and U.S. Pat. No. 5,570,813 to Clark, II show controlled, fluid delivery systems. However, none of the systems use a fuel injector.
Leighton et al describes a method and apparatus for metering liquid fuel for delivering to an engine. The patent also includes a method of metering fluids for cyclic delivery in variable discrete quantities comprising filling a fixed volume control chamber with the fluid each cycle, the control chamber being in direct communication with a dispensing chamber charged with a compressed gas, and then delivering a predetermined quantity of the fluid to the control chamber to displace fluid therefrom into the dispensing chamber and removing fluid from the control chamber to adjust the quantity of fluid displaced from the control chamber to the dispensing chamber.
Clark, II describes a delivery and management system for dispensing viscous material. Due to the type of material dispensed by this system it would not be obvious to use a fuel injector nozzle. In fact, the system would not operate correctly, if at all, using a fuel injector nozzle.
Only of some interest is EPO Patent No. 0220332 to Goudy which describes timing circuit for controlling the dispensing of a pelletized material and U.S. Pat. No. 4,852,802 to Iggulden et al and U.S. Pat. No. 4,962,522 to Marian which show a method for remotely controlling an irrigation system using a remote signal.
Only of minimal interest are U.S. Pat. No. 4,909,439 to Fu; U.S. Pat. No. 5,232,167 to McCormick et al; U.S. Pat. No. 5,244,180 to Wakeman et al; U.S. Pat. No. 5,289,627 to Cerny et al and U.S. Pat. No. 5,476,226 to Tomiita et al which show various types of solenoid valves used as fuel injectors.
There remains the need for an electronically controlled micro-dispensing apparatus which allows for controlling the duration and amount of the spray, as well as, the time interval between spraying and which is economical to manufacture and operate and portable and which allows for replacement of an empty container without replacing the entire apparatus.